Light emitting device and wafer

ABSTRACT

Provided is a light emitting device. A light emitting device includes a first n-type semiconductor layer, a first light emitting layer disposed on the first n-type semiconductor layer, a first p-type semiconductor layer disposed on the first light emitting layer, a second p-type semiconductor layer disposed on the first p-type semiconductor layer, a bonding layer disposed between the first p-type semiconductor layer and the second p-type semiconductor layer, a second light emitting layer disposed on the second p-type semiconductor layer, a second n-type semiconductor layer disposed on the second light emitting layer, a p-type electrode disposed on the second p-type semiconductor layer, a first n-type electrode disposed on the first n-type semiconductor layer, and a second n-type electrode disposed on the second n-type semiconductor layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Korean Patent Application No.10-2020-0098843 filed on Aug. 6, 2020, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein byreference.

BACKGROUND Technical Field

The present disclosure relates to a light emitting device and a wafer,and more particularly, to a wafer in which light emitting devicesemitting red light, green light, and blue light are formed together onone substrate.

Discussion of the Related Art

Display apparatuses used in computer monitors, TVs, mobile phones, etc.include an organic light emitting display (OLED) or the like that emitslight by itself and a liquid crystal display (LCD) or the like thatrequires a separate light source.

The display apparatuses are being applied in a wide range, not only tocomputer monitors and TVs but also to personal portable devices, andresearch is being conducted for a display apparatus having a largedisplay area with reduced volume and weight.

Recently, a display apparatus including light emitting devices (LEDs)has been spotlighted as a next-generation display apparatus. The LED,which is formed of an inorganic material rather than an organicmaterial, is superior in reliability and thus has a longer lifespan thanthe LCD or the OLED. In addition, the LED is capable of displaying ahigh-brightness image with excellent stability due to its fastlighting-up speed, excellent light-emitting efficiency, and strongresistance to impact.

SUMMARY

Accordingly, embodiments of the present disclosure are directed to alight emitting device and a wafer that substantially obviates one ormore of the problems due to limitations and disadvantages of the relatedart.

An object to be achieved by the present disclosure is to provide a lightemitting device capable of emitting light in one or more colors and awafer.

Another object to be achieved by the present disclosure is to provide alight emitting device formed together with other light emitting devicesemitting red light, green light, and blue light, and a wafer.

Another object to be achieved by the present disclosure is to provide alight emitting device and a wafer in which a plurality of light emittingdevices emitting red light, green light, and blue light is formed on thewafer to simplify a process of transferring the plurality of lightemitting devices.

Another object to be achieved by the present disclosure is to provide alight emitting device in which light emitting layers emitting light indifferent colors are stacked to reduce an area occupied by one lightemitting device, and a wafer.

Additional features and aspects will be set forth in the descriptionthat follows, and in part will be apparent from the description, or maybe learned by practice of the inventive concepts provided herein. Otherfeatures and aspects of the inventive concepts may be realized andattained by the structure particularly pointed out in the writtendescription, or derivable therefrom, and the claims hereof as well asthe appended drawings.

To achieve these and other aspects of the inventive concepts, asembodied and broadly described, a light emitting device comprises afirst n-type semiconductor layer, a first light emitting layer disposedon the first n-type semiconductor layer, a first p-type semiconductorlayer disposed on the first light emitting layer, a second p-typesemiconductor layer disposed on the first p-type semiconductor layer, abonding layer disposed between the first p-type semiconductor layer andthe second p-type semiconductor layer, a second light emitting layerdisposed on the second p-type semiconductor layer, a second n-typesemiconductor layer disposed on the second light emitting layer, ap-type electrode disposed on the second p-type semiconductor layer, afirst n-type electrode disposed on the first n-type semiconductor layer,and a second n-type electrode disposed on the second n-typesemiconductor layer. Therefore, since the first light emitting layer andthe second light emitting layer emitting light in different colors areincluded in one light emitting device, one light emitting device mayemit light in one or more colors.

In another aspect, a wafer comprises a substrate, and a plurality oflight emitting devices disposed on the substrate. Each of the pluralityof light emitting devices includes a first n-type semiconductor layerdisposed on the substrate, a first light emitting layer disposed on thefirst n-type semiconductor layer, a p-type semiconductor layer disposedon the first light emitting layer, a second light emitting layerdisposed on the p-type semiconductor layer, a second n-typesemiconductor layer disposed on the second light emitting layer, ap-type electrode disposed on the p-type semiconductor layer, a firstn-type electrode disposed on the first n-type semiconductor layer, and asecond n-type electrode disposed on the second n-type semiconductorlayer. Therefore, since the first light emitting layer and the secondlight emitting layer emitting light in different colors are disposed ina vertical direction, an area occupied by one light emitting device onthe substrate may be reduced.

Other detailed matters of the exemplary embodiments are included in thedetailed description and the drawings.

According to the present disclosure, red light and green light may beemitted together from one light emitting device, or red light and bluelight may be emitted together from one light emitting device.

According to the present disclosure, a transfer process may besimplified and a cost may be reduced by forming light emitting devicesemitting red light, green light, and blue light together on one wafer.

According to the present disclosure, an area occupied by one lightemitting device may be reduced and space utilization may be facilitatedby vertically stacking the light emitting layers emitting light indifferent colors.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the inventive concepts asclaimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this application, illustrate embodiments of the disclosure andtogether with the description serve to explain various principles. Inthe drawings:

FIG. 1 is a plan view of a wafer according to an exemplary embodiment ofthe present disclosure;

FIG. 2 is an enlarged plan view of the wafer according to an exemplaryembodiment of the present disclosure;

FIG. 3A is a plan view of a plurality of light emitting devicesaccording to an exemplary embodiment of the present disclosure;

FIG. 3B is a cross-sectional view taken along line IIIb-IIIb′ of FIG.3A;

FIG. 3C is a cross-sectional view taken along line IIIc-IIIc′ of FIG.3A;

FIG. 3D is a cross-sectional view taken along line IIId-IIId′ of FIG.3A;

FIGS. 4A to 4G are process diagrams for explaining a method ofmanufacturing the wafer according to an exemplary embodiment of thepresent disclosure; and

FIG. 5 is a cross-sectional view of a wafer according to anotherexemplary embodiment of the present disclosure.

DETAILED DESCRIPTION

Advantages and characteristics of the present disclosure and a method ofachieving the advantages and characteristics will be clear by referringto exemplary embodiments described below in detail together with theaccompanying drawings. However, the present disclosure is not limited tothe exemplary embodiments disclosed herein but will be implemented invarious forms. The exemplary embodiments are provided by way of exampleonly so that those skilled in the art can fully understand thedisclosures of the present disclosure and the scope of the presentdisclosure. Therefore, the present disclosure will be defined only bythe scope of the appended claims.

The shapes, sizes, ratios, angles, numbers, and the like illustrated inthe accompanying drawings for describing the exemplary embodiments ofthe present disclosure are merely examples, and the present disclosureis not limited thereto. Like reference numerals generally denote likeelements throughout the specification. Further, in the followingdescription of the present disclosure, a detailed explanation of knownrelated technologies may be omitted to avoid unnecessarily obscuring thesubject matter of the present disclosure. The terms such as “including,”“having,” and “comprising” used herein are generally intended to allowother components to be added unless the terms are used with the term“only”. Any references to singular may include plural unless expresslystated otherwise.

Components are interpreted to include an ordinary error range even ifnot expressly stated.

When the position relation between two parts is described using theterms such as “on”, “above”, “below”, and “next”, one or more parts maybe positioned between the two parts unless the terms are used with theterm “immediately” or “directly”.

When an element or layer is disposed “on” another element or layer,another layer or another element may be interposed directly on the otherelement or therebetween.

Although the terms “first”, “second”, and the like are used fordescribing various components, these components are not confined bythese terms. These terms are merely used for distinguishing onecomponent from the other components.

Therefore, a first component to be mentioned below may be a secondcomponent in a technical concept of the present disclosure.

Like reference numerals generally denote like elements throughout thespecification.

A size and a thickness of each component illustrated in the drawing areillustrated for convenience of description, and the present disclosureis not limited to the size and the thickness of the componentillustrated.

The features of various embodiments of the present disclosure can bepartially or entirely adhered to or combined with each other and can beinterlocked and operated in technically various ways, and theembodiments can be carried out independently of or in association witheach other.

Hereinafter, a light emitting device and a wafer according to exemplaryembodiments of the present disclosure will be described in detail withreference to accompanying drawings.

FIG. 1 is a plan view of a wafer according to an exemplary embodiment ofthe present disclosure. FIG. 2 is an enlarged plan view of the waferaccording to an exemplary embodiment of the present disclosure.Referring to FIGS. 1 and 2, the wafer 100 according to an exemplaryembodiment of the present disclosure includes a substrate 110 and aplurality of light emitting devices LEDs.

The substrate 110 is configured to support various components includedin the wafer 100. The plurality of light emitting devices LEDs is grownon the substrate 110. The substrate 110 may be formed of a material thatvaries depending on materials constituting the plurality of lightemitting devices LEDs. For example, the substrate 110 may be formed ofsapphire, gallium nitride GaN, silicon Si, silicon carbide SiC, or thelike, but is not limited thereto.

Referring to FIG. 1, the substrate 110 includes an active area AA and aninactive area IA. The active area AA is an area in which the pluralityof light emitting devices LEDs is formed, and the inactive area IAsurrounding the active area AA is an area in which an alignment key orthe like is disposed.

A flat area FA is disposed in a partial portion of an edge of thesubstrate 110. The flat area FA is a straight line portion of the edgeof the substrate 110 that is formed in a circular shape. The flat areaFA serves to distinguish a structure of the wafer 100. The flat area FAmay be used to determine the verticality and horizontality of the wafer100, and the flat area FA may be used as a reference line at the time ofprocessing the wafer 100.

Referring to FIG. 2, the plurality of light emitting devices LEDs isdisposed in the active area AA. The plurality of light emitting devicesLEDs are semiconductor devices emitting light when a voltage is appliedthereto. The light emitting devices LEDs may emit red light, greenlight, blue light, and the like, which may be combined to implementlight in various colors including white.

The plurality of light emitting devices LEDs may be formed by formingmaterials constituting the plurality of light emitting devices LEDs,such gallium nitride GaN, on the substrate 110 to grow crystal layers,cutting the crystal layers into individual chips, and forming electrodeson the chips. A process of forming the plurality of light emittingdevices LEDs will be described in detail below with reference to FIGS.4A to 4G.

The plurality of light emitting devices LEDs includes a first lightemitting device LED1 and a second light emitting device LED2. The firstlight emitting device LED1 is a light emitting device emitting red lightand green light, and the second light emitting device LED2 is a lightemitting device emitting red light and blue light.

The first light emitting device LED1 and the second light emittingdevice LED2 may be disposed at a predetermined interval on the substrate110 to correspond to respective transfer positions in a displayapparatus. Specifically, the red light, green light, and blue lightemitted from the first light emitting device LED1 and the second lightemitting device LED2 may be combined to display light in various colors.Thus, the first light emitting device LED1 emitting red light and greenlight and the second light emitting device LED2 emitting red light andblue light may be disposed adjacent to each other in the displayapparatus to form one pixel. When the first light emitting device LED1and the second light emitting device LED2 are formed adjacent to eachother on the substrate 110 to correspond a location of one pixel, thefirst light emitting device LED1 and the second light emitting deviceLED2 may be transferred at once without having to separately transfereach of the first light emitting device LED1 and the second lightemitting device LED2. Accordingly, the transfer process may besimplified. Thus, the first light emitting device LED1 and the secondlight emitting device LED2 may be disposed adjacent to each other in thesame row or in the same column, and one first light emitting device LED1and one second light emitting device LED2 adjacent to each other maycorrespond to one pixel. For example, a plurality of first lightemitting devices LED1 may be disposed in odd ones of a plurality ofrows, and a plurality of second light emitting devices LED2 may bedisposed in even ones of the plurality of rows. The first light emittingdevices LED1 and the second light emitting devices LED2 may bealternately disposed in a column direction. However, the plurality oflight emitting devices LEDs may be arranged in various forms accordingto how a plurality of pixels is arranged in the display apparatus, andthe arrangement of the plurality of light emitting devices LEDs is notlimited to what is illustrated in FIG. 2.

Hereinafter, the plurality of light emitting devices LEDs will bedescribed in detail with reference to FIGS. 3A to 3D.

FIG. 3A is a plan view of a plurality of light emitting devicesaccording to an exemplary embodiment of the present disclosure. FIG. 3Bis a cross-sectional view taken along line IIIb-IIIb′ of FIG. 3A. FIG.3C is a cross-sectional view taken along line IIIc-IIIc′ of FIG. 3A.FIG. 3D is a cross-sectional view taken along line IIId-IIId′ of FIG.3A.

Referring to FIGS. 3A, 3B, and 3D together, the first light emittingdevice LED1 among the plurality of light emitting devices LEDs includesa first n-type semiconductor layer N1, a first green light emittinglayer GE, a first p-type semiconductor layer P1, a bonding layer BD, asecond p-type semiconductor layer P2, a second light emitting layer RE,a second n-type semiconductor layer N2, a first n-type electrode NE1, asecond n-type electrode NE2, and a p-type electrode PE.

The first n-type semiconductor layer N1 is disposed on the substrate110, and the first p-type semiconductor layer P1 is disposed above thefirst n-type semiconductor layer N1. The first n-type semiconductorlayer N1 and the first p-type semiconductor layer P1 may be formed bydoping a specific material with n-type and p-type impurities,respectively. The first n-type semiconductor layer N1 may be formed bydoping a material such as gallium nitride GaN with an n-type impurity,and the first p-type semiconductor layer P1 may be formed by doping amaterial such as gallium nitride GaN with a p-type impurity. Forexample, the n-type impurity may be silicon Si, germanium Ge, tin Sn, orthe like, and the p-type impurity may be magnesium Mg, zinc Zn,beryllium Be, or the like, but the n-type and p-type impurities are notlimited thereto.

The first green light emitting layer GE is disposed between the firstn-type semiconductor layer N1 and the first p-type semiconductor layerP1. The first green light emitting layer GE may emit light by receivingholes and electrons that are supplied from the first n-typesemiconductor layer N1 and the first p-type semiconductor layer P1. Forexample, the first green light emitting layer GE may emit green light bymeans of the holes and electrons supplied from the first n-typesemiconductor layer N1 and the first p-type semiconductor layer P1. Thefirst green light emitting layer GE may be formed in a single-layerstructure or in a multi-quantum well (MQW) structure, and may be formedof, for example, indium gallium nitride InGaN or gallium nitride GaN,but is not limited thereto.

The second p-type semiconductor layer P2 is disposed above the firstp-type semiconductor layer P1, and the second n-type semiconductor layerN2 is disposed above the second p-type semiconductor layer P2. Thesecond n-type semiconductor layer N2 and the second p-type semiconductorlayer P2 may be formed by doping a specific material with n-type andp-type impurities, respectively. The second n-type semiconductor layerN2 may be formed by doping a material such as aluminum indium phosphideAlInP or gallium arsenide GaAs with an n-type impurity, and the secondp-type semiconductor layer P2 may be formed by doping a material such asgallium phosphide GaP with a p-type impurity. For example, the n-typeimpurity may be silicon Si, germanium Ge, tin Sn, or the like, and thep-type impurity may be magnesium Mg, zinc Zn, beryllium Be, or the like,but the n-type and p-type impurities are not limited thereto.

The second light emitting layer RE is disposed between the second p-typesemiconductor layer P2 and the second n-type semiconductor layer N2. Thesecond light emitting layer RE may emit light by receiving holes andelectrons that are supplied from the second n-type semiconductor layerN2 and the second p-type semiconductor layer P2. For example, the secondlight emitting layer RE may emit red light by means of the holes andelectrons supplied from the second n-type semiconductor layer N2 and thesecond p-type semiconductor layer P2. The second light emitting layer REmay be formed in a single-layer structure or in a multi-quantum well(MQW) structure, and may be formed of, for example, aluminum galliumindium phosphide AlGaInP, but is not limited thereto.

A partial portion of the first n-type semiconductor layer N1 protrudesoutward beyond the first green light emitting layer GE, the first p-typesemiconductor layer P1, the second p-type semiconductor layer P2, thesecond light emitting layer RE, and the second n-type semiconductorlayer N2. The first green light emitting layer GE, the first p-typesemiconductor layer P1, the second p-type semiconductor layer P2, thesecond light emitting layer RE, and the second n-type semiconductorlayer N2 may have a smaller size than the first n-type semiconductorlayer N1 to expose a top surface of the first n-type semiconductor layerN1. The partial portion of the first n-type semiconductor layer N1 maybe exposed beyond the first green light emitting layer GE, the firstp-type semiconductor layer P1, the second p-type semiconductor layer P2,the second light emitting layer RE, and the second n-type semiconductorlayer N2 to be electrically connected to the first n-type electrode NE1.In this case, an entire portion of the first green light emitting layerGE, an entire portion of the first p-type semiconductor layer P1, anentire portion of the second p-type semiconductor layer P2, an entireportion of the second light emitting layer RE, and an entire portion ofthe second n-type semiconductor layer N2 may overlap a partial portionof the first n-type semiconductor layer N1.

A partial portion of the second p-type semiconductor layer P2 protrudesoutward beyond the second light emitting layer RE and the second n-typesemiconductor layer N2. The second light emitting layer RE and thesecond n-type semiconductor layer N2 may have a smaller size than thesecond p-type semiconductor layer P2 to expose a top surface of thesecond p-type semiconductor layer P2. The partial portion of the secondp-type semiconductor layer P2 may be exposed beyond the second lightemitting layer RE and the second n-type semiconductor layer N2 to beelectrically connected to the p-type electrode PE. In addition, anentire portion of the second light emitting layer RE and an entireportion of the second n-type semiconductor layer N2 may overlap apartial portion of the second p-type semiconductor layer P2, a partialportion of the first p-type semiconductor layer P1, a partial portion ofthe first green light emitting layer GE, and a partial portion of thefirst n-type semiconductor layer N1.

The bonding layer BD is disposed between the first p-type semiconductorlayer P1 and the second p-type semiconductor layer P2. The bonding layerBD, which is a member for bonding the first p-type semiconductor layerP1 and the second p-type semiconductor layer P2 to each other, may beformed of a transparent material. The bonding layer BD may be formed ofa conductive material having a high transmittance, e.g. an anisotropicconductive film ACF or a metal mesh containing conductive particles.Accordingly, light emitted from the first green light emitting layer GEmay be emitted upward of the second n-type semiconductor layer N2 afterpassing through the bonding layer BD having a high transmittance.

The first n-type electrode NE1 is disposed on the first n-typesemiconductor layer N1, and the second n-type electrode NE2 is disposedon the second n-type semiconductor layer N2. The first n-type electrodeNE1 may be in contact with the top surface of the first n-typesemiconductor layer N1 exposed beyond the first green light emittinglayer GE to be electrically connected to the first n-type semiconductorlayer N1, and the second n-type electrode NE2 may be in contact with atop surface of the second n-type semiconductor layer N2 to beelectrically connected to the second n-type semiconductor layer N2.

The p-type electrode PE is disposed on the second p-type semiconductorlayer P2. The p-type electrode PE may be in contact with the secondp-type semiconductor layer P2 exposed beyond the second light emittinglayer RE to be electrically connected to the second p-type semiconductorlayer P2. The p-type electrode PE may also be electrically connected tothe first p-type semiconductor layer P1.

In this case, the bonding layer BD may be formed of a conductivematerial. When the bonding layer BD is formed of a conductive material,the p-type electrode PE contacting the second p-type semiconductor layerP2 may also be electrically connected to the first p-type semiconductorlayer P1 through the bonding layer BD. For example, when the bondinglayer BD is formed of a conductive material having a high transmittance,the first p-type semiconductor layer P1 and the second p-typesemiconductor layer P2 may be electrically connected to each otherthrough the bonding layer BD, and the p-type electrode PE contacting thesecond p-type semiconductor layer P2 may also be electrically connectedto the first p-type semiconductor layer P1. Therefore, the p-typeelectrode PE may be electrically connected to both the first p-typesemiconductor layer P1 and the second p-type semiconductor layer P2 bycontacting the top surface of the second p-type semiconductor layer P2.

Meanwhile, the first n-type electrode NE1 may be thicker than the secondn-type electrode NE2 and the p-type electrode PE. The first n-typeelectrode NE1 is disposed on the top surface of the first n-typesemiconductor layer N1 that is closest to the substrate 110, and thep-type electrode PE is disposed on the top surface of the second p-typesemiconductor layer P2 that is disposed above the first n-typesemiconductor layer N1. In addition, the second n-type electrode NE2 isdisposed on the top surface of the second n-type semiconductor layer N2that is disposed on the uppermost side. Thus, the first n-type electrodeNE1 may be disposed to be closer to the substrate 110 than the secondn-type electrode NE2 and the p-type electrode PE, which causesdifferences in height level between the first n-type electrode NE1, thesecond n-type electrode NE2, and the p-type electrode PE. If there aredifferences in height level between the first n-type electrode NE1, thesecond n-type electrode NE2, and the p-type electrode PE, the pluralityof light emitting devices LEDs may be distorted in the process oftransferring the plurality of light emitting devices LEDs. Thus, thedifferences in height level between the first n-type electrode NE1, thesecond n-type electrode NE2, and the p-type electrode PE may beminimized by forming the first n-type electrode NE1 to be thicker thanthe second n-type electrode NE2 and the p-type electrode PE.

In this case, the second n-type electrode NE2, which overlaps the firstgreen light emitting layer GE and the second light emitting layer RE,and the p-type electrode PE, which overlaps the first green lightemitting layer GE, may be formed of a transparent conductive material,e.g. tin oxide TO, indium tin oxide ITO, indium zinc oxide IZO, orindium tin zinc oxide ITZO. In addition, even if the first n-typeelectrode NE1 is formed of an opaque conductive material, the firstn-type electrode NE1, which does not overlap the first green lightemitting layer GE and the second light emitting layer RE, may notinterfere with propagation of light emitted from the first green lightemitting layer GE and the second light emitting layer RE. Thus, thefirst n-type electrode NE1 may be formed of an opaque conductivematerial that can be formed to have a large thickness, e.g. gold Au.

Meanwhile, the first green light emitting layer GE and the second lightemitting layer RE may emit light independently from each other. As anexample, when a voltage is applied only to the first n-type electrodeNE1 and the p-type electrode PE among the first n-type electrode NE1,the second n-type electrode NE2, and the p-type electrode PE, the firstgreen light emitting layer GE may emit light through the first n-typesemiconductor layer N1 electrically connected to the first n-typeelectrode NE1 and the first p-type semiconductor layer P1 electricallyconnected to the p-type electrode PE, while the second light emittinglayer RE does not emit light because no voltage is applied to the secondn-type electrode NE2. As another example, when a voltage is applied onlyto the second n-type electrode NE2 and the p-type electrode PE among thefirst n-type electrode NE1, the second n-type electrode NE2, and thep-type electrode PE, the second light emitting layer RE may emit lightthrough the second n-type semiconductor layer N2 electrically connectedto the second n-type electrode NE2 and the second p-type semiconductorlayer P2 electrically connected to the p-type electrode PE, while thefirst green light emitting layer GE does not emit light because novoltage is applied to the first n-type electrode NE1. As anotherexample, when a voltage is applied to all of the first n-type electrodeNE1, the second n-type electrode NE2, and the p-type electrode PE, thefirst green light emitting layer GE and the second light emitting layerRE may emit light simultaneously. Thus, the first green light emittinglayer GE and the second light emitting layer RE may be controlled toemit light independently from each other by selectively applying avoltage to the first n-type electrode NE1 and the second n-typeelectrode NE2 while applying the voltage to the p-type electrode PE.

Next, an insulating layer IL surrounding the first light emitting deviceLED1 is disposed. In order to avoid an electrical short of each of thefirst n-type semiconductor layer N1, the first p-type semiconductorlayer P1, the second p-type semiconductor layer P2, and the secondn-type semiconductor layer N2, the insulating layer IL may be disposedto surround a partial portion of the first light emitting device LED1.Specifically, the insulating layer IL may cover an entire portion of aside surface and a partial portion of a top surface of the first n-typesemiconductor layer N1, an entire portion of a side surface of the firstgreen light emitting layer GE, an entire portion of a side surface ofthe first p-type semiconductor layer P1, an entire portion of a sidesurface of the bonding layer BD, an entire portion of a side surface anda partial portion of a top surface of the second p-type semiconductorlayer P2, an entire portion of a side surface of the second lightemitting layer RE, and an entire portion of a side surface and a partialportion of a top surface of the second n-type semiconductor layer N2.

Referring to FIGS. 3A, 3C, and 3D together, the second light emittingdevice LED2 among the plurality of light emitting devices LEDs includesa first n-type semiconductor layer N1, a first blue light emitting layerBE, a first p-type semiconductor layer P1, a bonding layer BD, a secondp-type semiconductor layer P2, a second light emitting layer RE, asecond n-type semiconductor layer N2, a first n-type electrode NE1, asecond n-type electrode NE2, and a p-type electrode PE. The second lightemitting device LED2 substantially has the same configuration as thefirst light emitting device LED1, except that the first blue lightemitting layer BE is included instead of the first green light emittinglayer GE.

The first blue light emitting layer BE is disposed between the firstn-type semiconductor layer N1 and the first p-type semiconductor layerP1. The first blue light emitting layer BE may emit light by receivingholes and electrons that are supplied from the first n-typesemiconductor layer N1 and the first p-type semiconductor layer P1. Forexample, the first blue light emitting layer BE may emit blue light bymeans of the holes and electrons supplied from the first n-typesemiconductor layer N1 and the first p-type semiconductor layer P1. Thefirst blue light emitting layer BE may be formed in a single-layerstructure or in a multi-quantum well (MQW) structure, and may be formedof, for example, indium gallium nitride InGaN or gallium nitride GaN,but is not limited thereto.

Hereinafter, a method of manufacturing a wafer 100 according to anexemplary embodiment of the present disclosure will be described withreference to FIGS. 4A to 4G.

FIGS. 4A to 4G are process diagrams for explaining a method ofmanufacturing the wafer according to an exemplary embodiment of thepresent disclosure. Specifically, FIGS. 4A to 4G are schematiccross-sectional views for explaining a process of forming a plurality oflight emitting devices LEDs on a substrate 110.

Referring to FIG. 4A, a first epitaxial layer EP1 is formed on thesubstrate 110. The first epitaxial layer EP1 is provided to form aplurality of light emitting devices LEDs. In the first epitaxial layerEP1, materials constituting each of a first n-type semiconductor layerN1, a first green light emitting layer GE and a first p-typesemiconductor layer P1 or each of a first n-type semiconductor layer N1,a first blue light emitting layer BE, and a first p-type semiconductorlayer P1 may be sequentially stacked. In the following description, forconvenience of explanation, it is assumed that the first epitaxial layerEP1 includes a material constituting the first blue light emitting layerBE. However, the first epitaxial layer EP1 may include a materialconstituting the first green light emitting layer GE, and is not limitedthereto.

First, a first n-type semiconductor material layer NL1 may be formed bygrowing a semiconductor crystal on the substrate 110. Subsequently, afirst blue light emitting material layer BEL and a first p-typesemiconductor material layer PL1 may be formed by growing semiconductorcrystals on the first n-type semiconductor material layer NL1. In thiscase, the first blue light emitting material layer BEL may be grown byinheriting the crystallinity of the first n-type semiconductor materiallayer NL1, and the first p-type semiconductor material layer PL1 grownon the first blue light emitting material layer BEL may be grown byinheriting the crystallinity of the first blue light emitting materiallayer BEL. That is, the first epitaxial layer EP1 may be formed bysequentially growing the first n-type semiconductor material layer NL1,the first blue light emitting material layer BEL, and the first p-typesemiconductor material layer PL1 on the substrate 110.

In this case, the first epitaxial layer EP1 may be grown on thesubstrate 110 by a metal organic chemical vapor deposition (MOCVD)method, a sputtering method, or the like, but the method of growing thefirst epitaxial layer EP1 is not limited thereto.

Subsequently, referring to FIG. 4B, a partial portion of each of thefirst p-type semiconductor material layer PL1 and the first blue lightemitting material layer BEL is removed, the removed partial portionoverlapping an area where first light emitting devices LED1 among theplurality of light emitting devices LEDs are to be formed. Accordingly,only the first n-type semiconductor material layer NL1 may be disposedon a partial area of the substrate 110 overlapping the area where thefirst light emitting devices LED1 are to be formed, while the firstn-type semiconductor material layer NL1, the first blue light emittingmaterial layer BEL, and the first p-type semiconductor material layerPL1 may be disposed on the other partial area of the substrate 110overlapping an area where second light emitting devices LED2 are to beformed.

Subsequently, referring to FIG. 4C, a second epitaxial layer EP2 isformed on the substrate 110. In the second epitaxial layer EP2,respective materials constituting the first green light emitting layerGE and the first p-type semiconductor layer P1 may be sequentiallystacked.

First, a first green light emitting material layer GEL may be formed bygrowing a semiconductor crystal on the substrate 110. Subsequently, afirst p-type semiconductor material layer PL1′ may be formed by growinga semiconductor crystal on the first green light emitting material layerGEL.

Meanwhile, the second epitaxial layer EP2 may be formed over an entiresurface of the substrate 110. The first green light emitting materiallayer GEL and the first p-type semiconductor material layer PL1′ may beformed over the entire surface of the substrate 110 to cover the firstp-type semiconductor material layer PL1 and the first n-typesemiconductor material layer NL1 of the first epitaxial layer EP1. Inthis case, a partial portion of the second epitaxial layer EP2 formed onthe first p-type semiconductor material layer PL1 of the first epitaxiallayer EP1 may be removed for a process of bonding a third epitaxiallayer EP3, which will be described below. The reason for removing thepartial portion of the second epitaxial layer EP2 formed on the firstp-type semiconductor material layer PL1 of the first epitaxial layer EP1is that top surfaces of the first p-type semiconductor material layerPL1 of the first epitaxial layer EP1 and the first p-type semiconductormaterial layer PL1′ of the second epitaxial layer EP2 need to becoplanar in order to bond the third epitaxial layer EP3 to the firstepitaxial layers EP1 and second epitaxial layers EP2. Accordingly, onlythe first green light emitting material layer GEL and the first p-typesemiconductor material layer PL1′ of the second epitaxial layer EP2formed on the first n-type semiconductor material layer Nil of the firstepitaxial layer EP1 may remain on the substrate 110.

Alternatively, the second epitaxial layer EP2 may be formed only on thefirst n-type semiconductor material layer Nil exposed beyond the firstblue light emitting material layer BEL. The first green light emittingmaterial layer GEL and the first p-type semiconductor material layerPL1′ of the second epitaxial layer EP2 may be formed to cover only thefirst n-type semiconductor material layer NL1 of the first epitaxiallayer EP1. For example, the second epitaxial layer EP2 may be grown onlyon the first n-type semiconductor material layer NL1, after forming aseparate insulating film covering the first p-type semiconductormaterial layer PL1 of the first epitaxial layer EP1 so that the secondepitaxial layer EP2 cannot be grown on the first p-type semiconductormaterial layer PL1 of the first epitaxial layer EP1. When the secondepitaxial layer EP2 is grown only on the first n-type semiconductormaterial layer NL1 of the first epitaxial layer EP1, the process ofremoving the partial portion of the second epitaxial layer EP2 coveringthe first p-type semiconductor layer P1 of the first epitaxial layer EP1may be omitted. However, the growth area of the second epitaxial layerEP2 may vary depending on design, not being limited to what is describedabove.

Thus, the respective materials constituting the first n-typesemiconductor layer N1, the first blue light emitting layer BE, and thefirst p-type semiconductor layer P1 of the second light emitting deviceLED2, and the first n-type semiconductor layer N1 of the first lightemitting device LED1 may be formed by growing the first epitaxial layerEP1 on the substrate 110, and the respective materials constituting thefirst green light emitting layer GE and the first p-type semiconductorlayer P1 of the first light emitting device LED1 may be formed bygrowing the second epitaxial layer EP2 on the substrate 110.

Subsequently, referring to FIG. 4D, the third epitaxial layer EP3 isbonded onto the first and second epitaxial layers EP1 and EP2. Afterforming a bonding layer BD between the first and second epitaxial layersEP1 and EP2 and the third epitaxial layer EP3, the third epitaxial layerEP3 may be bonded to the first epitaxial layer EP1 and the secondepitaxial layer EP2.

First, the third epitaxial layer EP3 may be formed on a temporarysubstrate ST to form the plurality of light emitting devices LEDs. Inthe third epitaxial layer EP3, respective materials constituting asecond n-type semiconductor layer N2, a second light emitting layer RE,and a second p-type semiconductor layer P2 may be sequentially stacked.

A second n-type semiconductor material layer NL2 may be formed bygrowing a semiconductor crystal on the temporary substrate ST.Subsequently, a second light emitting material layer REL and a secondp-type semiconductor material layer PL2 may be formed by growingsemiconductor crystals on the second n-type semiconductor material layerNL2. Thus, the third epitaxial layer EP3 may be formed by sequentiallygrowing the second n-type semiconductor material layer NL2, the secondlight emitting material layer REL, and the second p-type semiconductormaterial layer PL2 on the temporary substrate ST.

In this case, the third epitaxial layer EP3 may be formed on thetemporary substrate ST that is different from the substrate 110 on whichthe first epitaxial layer EP1 and the second epitaxial layer EP2 aregrown, because of the growth efficiency of the third epitaxial layerEP3. Specifically, the first epitaxial layer EP1, the second epitaxiallayer EP2, and the third epitaxial layer EP3, each including a lightemitting material layer emitting light in a different color from theothers, may vary in growth efficiency depending on what type ofsubstrate 110 is used. As an example, when the substrate 110 is agallium nitride substrate or a sapphire substrate, the first epitaxiallayer EP1 and the second epitaxial layer EP2 including the first bluelight emitting material layer BEL and the first green light emittingmaterial layer GEL, respectively, may be easily grown on the substrate110, whereas the third epitaxial layer EP3 including the second lightemitting material layer REL, which emits red light, may be difficult togrow on the gallium nitride substrate or the sapphire substrate due toits low growth efficiency thereon. As another example, when thesubstrate 110 is a gallium arsenide substrate or a gallium phosphorussubstrate, the third epitaxial layer EP3 including the second lightemitting material layer REL, which emits red light, may be efficientlygrown on the substrate 110. Thus, the first epitaxial layer EP1 and thesecond epitaxial layer EP2 may be grown on one substrate 110, and thethird epitaxial layer EP3 may be grown on the temporary substrate STthat is different from the substrate 110 on which the first epitaxiallayer EP1 and the second epitaxial layer EP2 are grown.

Next, the bonding layer BD may be formed on an upper side of the thirdepitaxial layer EP3 or on upper sides of the first epitaxial layer EP1and the second epitaxial layer EP2. For example, the bonding layer BDmay be formed on the second p-type semiconductor material layer PL2 ofthe third epitaxial layer EP3, or the bonding layer BD may be formed onthe first p-type semiconductor material layers PL1 and PL1′ of the firstepitaxial layer EP1 and the second epitaxial layer EP2.

Subsequently, after positioning the temporary substrate ST so that thethird epitaxial layer EP3 faces the first epitaxial layer EP1 and thesecond epitaxial layer EP2, the third epitaxial layer EP3 may be bondedto the first epitaxial layer EP1 and the second epitaxial layer EP2.After positioning the temporary substrate ST and the substrate 110 sothat the second p-type semiconductor material layer PL2 of the thirdepitaxial layer EP3 and the first p-type semiconductor material layersPL1 and PL1′ of the first and second epitaxial layers EP1 and EP2 faceeach other with the bonding layer BD interposed therebetween, the firstand second epitaxial layers EP1 and EP2 and the third epitaxial layerEP3 may be bonded to each other by joining the substrate 110 and thetemporary substrate ST together.

Referring to FIG. 4E, after completing the bonding between the first andsecond epitaxial layers EP1 and EP2 and the third epitaxial layer EP3,the temporary substrate ST is removed. The temporary substrate ST may beseparated from the third epitaxial layer EP3. For example, the temporarysubstrate ST may be separated from the third epitaxial layer EP3 using alaser lift-off (LLO) technique.

According to the laser lift-off technique, when the temporary substrateST is irradiated with a laser, laser absorption occurs at an interfacebetween the second n-type semiconductor material layer NL2 and thetemporary substrate ST, thereby separating the temporary substrate STfrom the second n-type semiconductor material layer NL2. The temporarysubstrate ST may be separated by a method other than the laser lift-offmethod, but the method for separating the temporary substrate ST is notlimited thereto.

Next, referring to FIG. 4F, partial portions of the first epitaxiallayer EP1, the second epitaxial layer EP2, and the third epitaxial layerEP3 are etched. A first n-type semiconductor layer N1, a first greenlight emitting layer GE, a first p-type semiconductor layer P1, abonding layer BD, a second p-type semiconductor layer P2, a second lightemitting layer RE, and a second n-type semiconductor layer N2 of thefirst light emitting device LED1 may be formed by etching the firstepitaxial layer EP1, the second epitaxial layer EP2, and the thirdepitaxial layer EP3. Also, a first n-type semiconductor layer N1, afirst blue light emitting layer BE, a first p-type semiconductor layerP1, a bonding layer BD, a second p-type semiconductor layer P2, a secondlight emitting layer RE, and a second n-type semiconductor layer N2 ofthe second light emitting device LED2 may be formed by etching the firstepitaxial layer EP1, the second epitaxial layer EP2, and the thirdepitaxial layer EP3.

First, the second n-type semiconductor layer N2 and the second lightemitting layer RE for each of the first light emitting device LED1 andthe second light emitting device LED2 may be formed by etching thesecond n-type semiconductor material layer NL2 and the second lightemitting material layer REL of the third epitaxial layer EP3.

Subsequently, the second p-type semiconductor layer P2, the bondinglayer BD, the first p-type semiconductor layer P1, and the first greenlight emitting layer GE of the first light emitting device LED1 may beformed by etching the second p-type semiconductor material layer PL2,the bonding layer BD, the first p-type semiconductor material layerPL1′, and the first green light emitting material layer GEL exposedbeyond the second n-type semiconductor layer N2 and the second lightemitting layer RE. Also, the second p-type semiconductor layer P2, thebonding layer BD, the first p-type semiconductor layer P1, and the firstblue light emitting layer BE of the second light emitting device LED2may be formed by etching the same width of the second p-typesemiconductor material layer PL2, the bonding layer BD, the first p-typesemiconductor material layer PL1, and the first blue light emittingmaterial layer BEL exposed beyond the second n-type semiconductor layerN2 and the second light emitting layer RE.

Next, the respective first n-type semiconductor layers N1 of the firstlight emitting device LED1 and the second light emitting device LED2 maybe formed by etching the first n-type semiconductor material layer NL1exposed beyond the first green light emitting layer GE and the firstblue light emitting layer BE.

Thus, by etching the partial portions of the first epitaxial layer EP1,the second epitaxial layer EP2, and the third epitaxial layer EP3, thefirst n-type semiconductor layer N1, the first green light emittinglayer GE, the first p-type semiconductor layer P1, the bonding layer BD,the second p-type semiconductor layer P2, the second light emittinglayer RE, and the second n-type semiconductor layer N2 of the firstlight emitting device LED1 may be formed, and the first n-typesemiconductor layer N1, the first blue light emitting layer BE, thefirst p-type semiconductor layer P1, the bonding layer BD, the secondp-type semiconductor layer P2, the second light emitting layer RE, andthe second n-type semiconductor layer N2 of the second light emittingdevice LED2 may be formed.

Lastly, referring to FIG. 4G, a first n-type electrode NE1, a secondn-type electrode NE2, a p-type electrode PE, and an insulating layer ILare formed for each of the plurality of light emitting devices LEDs.

In the first light emitting device LED1, the first n-type electrode NE1may be formed on the first n-type semiconductor layer N1, the secondn-type electrode NE2 may be formed on the second n-type semiconductorlayer N2, and the p-type electrode PE may be formed on the second p-typesemiconductor layer P2. In this case, the first n-type electrode NE1,which is disposed to be closest to the substrate 110 among the firstn-type electrode NE1, the second n-type electrode NE2, and the p-typeelectrode PE without overlapping the first green light emitting layer GEand the second light emitting layer RE, may be formed of an opaqueconductive material that can be formed to have a large thickness, e.g.gold, to reduce a difference in height level. The second n-typeelectrode NE2, which overlaps the first green light emitting layer GEand the second light emitting layer RE, and the p-type electrode PE,which overlaps the first green light emitting layer GE, may be formed ofa transparent material, e.g. indium tin oxide, to allow light emittedfrom the first green light emitting layer GE and the second lightemitting layer RE to be transmitted therethrough. Since the first n-typeelectrode NE1 is formed of a different material with a differentthickness from the second n-type electrode NE2 and the p-type electrodePE, a process of forming the first n-type electrode NE1 may be performedseparately from a process of forming the second n-type electrode NE2 andthe p-type electrode PE. In this case, the orders of the process offorming the first n-type electrode NE1 and the process of forming thesecond n-type electrode NE2 and the p-type electrode PE may varydepending on design.

In the second light emitting device LED2, like the first light emittingdevice LED1, the first n-type electrode NE1 may be formed on the firstn-type semiconductor layer N1, the second n-type electrode NE2 may beformed on the second n-type semiconductor layer N2, and the p-typeelectrode PE may be formed on the second p-type semiconductor layer P2.In this case, the first n-type electrode NE1, which is disposed to beclosest to the substrate 110 among the first n-type electrode NE1, thesecond n-type electrode NE2, and the p-type electrode PE withoutoverlapping the first blue light emitting layer BE and the second lightemitting layer RE, may be formed of an opaque material, e.g. gold, witha relatively large thickness. The second n-type electrode NE2, whichoverlaps the first blue light emitting layer BE and the second lightemitting layer RE, and the p-type electrode PE, which overlaps the firstblue light emitting layer BE, may be formed of a transparent material,e.g. indium tin oxide, to allow light emitted from the first blue lightemitting layer BE and the second light emitting layer RE to betransmitted therethrough.

In addition, the first n-type electrode NE1 of the first light emittingdevice LED1 and the first n-type electrode NE1 of the second lightemitting device LED2 may be formed of the same material in the sameprocess, and the second n-type electrode NE2 and the p-type electrode PEof the first light emitting device LED1 and the second n-type electrodeNE2 and the p-type electrode PE of the second light emitting device LED2may also be formed of the same material in the same process.

Subsequently, the insulating layer IL surrounding each of the firstlight emitting device LED1 and the second light emitting device LED2 isformed. The insulating layer IL may cover each of the first lightemitting device LED1 and the second light emitting device LED2, exceptrespective partial portions of the first n-type electrode NE1, thesecond n-type electrode NE2, and the p-type electrode PE of each of thefirst light emitting device LED1 and the second light emitting deviceLED2.

Meanwhile, the insulating layer IL may be formed before forming thefirst n-type electrode NE1, the second n-type electrode NE2, and thep-type electrode PE of each of the first light emitting device LED1 andthe second light emitting device LED2, or may be formed after formingthe first n-type electrode NE1, the second n-type electrode NE2, and thep-type electrode PE of each of the first light emitting device LED1 andthe second light emitting device LED2. As an example, after forming theinsulating layer IL covering the first n-type semiconductor layer N1,the first green light emitting layer GE and the first blue lightemitting layer BE, the first p-type semiconductor layer P1, the bondinglayer BD, the second p-type semiconductor layer P2, the second lightemitting layer RE, and the second n-type semiconductor layer N2 for eachof the first and second light emitting devices LED1 and LED2, contactholes may be formed to expose partial portions of the top surfaces ofthe first n-type semiconductor layer N1, the second n-type semiconductorlayer N2, and the second p-type semiconductor layer P2. Then, the firstn-type electrode NE1, the second n-type electrode NE2, and the p-typeelectrode PE may be formed to fill the contact holes formed in theinsulating layer IL, thereby completing the formation of the wafer 100in which the first light emitting device LED1 and the second lightemitting device LED2 are formed. As another example, in a state whereall of the first n-type electrode NE1, the second n-type electrode NE2,and the p-type electrode PE are formed for each of the first and secondlight emitting devices LED1 and LED2, the insulating layer IL may beformed over the entire surface of the substrate 110 with contact holesformed therein to expose the first n-type electrode NE1, the secondn-type electrode NE2, and the p-type electrode PE from the insulatinglayer IL, thereby completing the formation of the wafer 100 in which thefirst light emitting device LED1 and the second light emitting deviceLED2 are formed. However, it may vary depending on design which orderthe insulating layer IL is formed in, not being limited to what isdescribed above.

In the wafer 100 according to an exemplary embodiment of the presentdisclosure, the plurality of light emitting devices LEDs emitting redlight, green light, and blue light may be formed on one substrate 110together, thereby simplifying a transfer process. The first lightemitting device LED1 and the second light emitting device LED2 may beformed on one substrate 110 together, the first light emitting deviceLED1 including the first green light emitting layer GE, which emitsgreen light, and the second light emitting layer RE, which emits redlight, and the second light emitting device LED2 including the firstblue light emitting layer BE, which emits blue light, and the secondlight emitting layer RE, which emits red light. Specifically, the firstepitaxial layer EP1 and the second epitaxial layer EP2 are grown on thesubstrate 110 because the first green light emitting layer GE and thefirst blue light emitting layer BE included in the first epitaxial layerEP1 and the second epitaxial layer EP2, respectively, are easy to growon one substrate 110, and the third epitaxial layer EP3 including thesecond light emitting layer RE which is grown on the temporary substrateST is grown on the temporary substrate ST. Then, the bonding layer BDmay be formed between the first and second epitaxial layers EP1 and EP2and the third epitaxial layer EP3 to bond the third epitaxial layer EP3onto the first and second epitaxial layers EP1 and EP2. Thereafter, thefirst epitaxial layer EP1, the second epitaxial layer EP2, and the thirdepitaxial layer EP3 may be patterned to have a plurality of patterns,and electrodes may be formed thereon, such that the plurality of lightemitting devices LEDs may be formed. Accordingly, in the wafer 100according to an exemplary embodiment of the present disclosure, lightemitting devices LED including a red light emitting layer, a green lightemitting layer, and a blue light emitting layer may be formed on one thesubstrate 110. For example, when a light emitting device including a redlight emitting layer, a light emitting device including a green lightemitting layer, and a light emitting device including a blue lightemitting layer are transferred to a backplane after being formed ondifferent substrates, the number of transfer processes may increase, anda misalignment may occur for each of the plurality of light emittingdevices. In contrast, in the wafer 100 according to an exemplaryembodiment of the present disclosure, since the plurality of lightemitting devices LEDs including a red light emitting layer, a greenlight emitting layer, and a blue light emitting layer is formed on onesubstrate 110, the plurality of light emitting devices LEDs may betransferred to a backplane at once, thereby minimizing misalignmentsbetween the red light emitting layer, the green light emitting layer,and the blue light emitting layer, simplifying a transfer process, andreducing a cost.

In the wafer 100 according to an exemplary embodiment of the presentdisclosure, the first green light emitting layer GE and the second lightemitting layer RE included in the first light emitting device LED1 maybe vertically stacked, and the first blue light emitting layer BE andthe second light emitting layer RE included in the second light emittingdevice LED2 may be vertically stacked, thereby reducing an area occupiedby each of the plurality of light emitting devices LEDs. Specifically,the second light emitting layer RE, which is a red light emitting layer,may be disposed above each of the first green light emitting layer GEand the first blue light emitting layer BE, rather than being disposedon the same plane as each of the first green light emitting layer GE andthe first blue light emitting layer BE, thereby reducing an area of thesubstrate 110 occupied by the second light emitting layer RE. If thesecond light emitting layer RE is disposed on the same plane as each ofthe first green light emitting layer GE and the first blue lightemitting layer BE, it is required to secure a space for disposing thesecond light emitting layer RE on the substrate 110, and thus, thenumber of light emitting devices LEDs that can be accommodated on onesubstrate 110 may be restricted. In contrast, in the wafer 100 accordingto an exemplary embodiment of the present disclosure, the second lightemitting layer RE is stacked in a vertical direction with respect toeach of the first green light emitting layer GE and the first blue lightemitting layer BE, thereby reducing an area occupied by the second lightemitting layer RE and increasing the number of light emitting devicesLEDs that can be accommodated on one substrate 110. Therefore, in thewafer 100 according to an exemplary embodiment of the presentdisclosure, since the light emitting layers emitting light in differentcolors are stacked, it is possible to reduce an area occupied by onelight emitting device LED and facilitate space utilization.

FIG. 5 is a cross-sectional view of a wafer according to anotherexemplary embodiment of the present disclosure. When compared to thewafer 100 of FIGS. 1 to 3D, the wafer 500 of FIG. 5 substantially hasthe same configuration, while being different only in a bonding layerBD′ and a p-type electrode PE′. Thus, the overlapping description forthe same configuration will be omitted.

Referring to FIG. 5, the bonding layer BD′ for each of the first lightemitting device LED1 and the second light emitting device LED2 may beformed of a non-conductive material having a high transmittance. Thebonding layer BD′ may be formed of a resin, such as benzocyclobutene(BCB), to bond the first p-type semiconductor layer P1 and the secondp-type semiconductor layer P2 thereto.

When the bonding layer BD′ is formed of a non-conductive material, thep-type electrode PE′ may penetrate through the second p-typesemiconductor layer P2 and the bonding layer BD′ to be electricallyconnected to the first p-type semiconductor layer P1. Specifically, whenthe bonding layer BD′ is formed of a non-conductive material, the firstp-type semiconductor layer P1 and the second p-type semiconductor layerP2 disposed with the bonding layer BD′ interposed therebetween may beelectrically insulated from each other. Accordingly, in order toelectrically connect the p-type electrode PE′ disposed on the topsurface of the second p-type semiconductor layer P2 to the first p-typesemiconductor layer P1, contact holes for exposing the first p-typesemiconductor layer P1 may be formed in the second p-type semiconductorlayer P2 and the bonding layer BD′, and the p-type electrode PE′ may beelectrically connected to the first p-type semiconductor layer P1through the contact holes.

In the wafer 500 according to another exemplary embodiment of thepresent disclosure, the p-type electrode PE′ may be designed accordingto the material of the bonding layer BD or BD′. For example, as in thewafer 100 of FIGS. 1 to 3D, when the bonding layer BD is formed of aconductive material, the p-type electrode PE may be electricallyconnected to both the first p-type semiconductor layer P1 and the secondp-type semiconductor layer P2 by contacting the top surface of thesecond p-type semiconductor layer P2. In contrast, as in the wafer 500of FIG. 5, when the bonding layer BD′ is formed of a non-conductivematerial, a partial portion of the p-type electrode PE′ may penetratethrough the second p-type semiconductor layer P2 and the bonding layerBD′ to be electrically connected to the first p-type semiconductor layerP1. Therefore, an electrical connection between the p-type electrode PE′and the first and second p-type semiconductor layers P1 and P2 may bedesigned in various manners in consideration of the material of thebonding layer BD or BD′.

The exemplary embodiments of the present disclosure can also bedescribed as follows:

According to an aspect of the present disclosure, there is provided alight emitting device, comprising: The light emitting device includes afirst n-type semiconductor layer. The light emitting device furtherincludes a first light emitting layer disposed on the first n-typesemiconductor layer. The light emitting device further includes a firstp-type semiconductor layer disposed on the first light emitting layer.The light emitting device further includes a second p-type semiconductorlayer disposed on the first p-type semiconductor layer. The lightemitting device further includes a bonding layer disposed between thefirst p-type semiconductor layer and the second p-type semiconductorlayer. The light emitting device further includes a second lightemitting layer disposed on the second p-type semiconductor layer. Thelight emitting device further includes a second n-type semiconductorlayer disposed on the second light emitting layer. The light emittingdevice further includes a p-type electrode disposed on the second p-typesemiconductor layer. The light emitting device further includes a firstn-type electrode disposed on the first n-type semiconductor layer. Thelight emitting device further includes

a second n-type electrode disposed on the second n-type semiconductorlayer.

A partial portion of the first n-type semiconductor layer may protrudesoutward beyond the first light emitting layer, the first p-typesemiconductor layer, the second p-type semiconductor layer, the secondlight emitting layer, and the second n-type semiconductor layer. Thefirst n-type electrode may be disposed on the partial portion of thefirst n-type semiconductor layer protruding outward beyond the firstlight emitting layer and the second light emitting layer.

An entire portion of the second p-type semiconductor layer may overlapthe first light emitting layer, a partial portion of the second p-typesemiconductor layer protrudes outward beyond the second light emittinglayer and the second n-type semiconductor layer. The p-type electrodemay be disposed on the partial portion of the second p-typesemiconductor layer protruding outward beyond the second light emittinglayer.

The first n-type electrode may have a larger thickness than the secondn-type electrode. The first n-type electrode may be formed of an opaqueconductive material. The second n-type electrode may be formed of atransparent conductive material.

The bonding layer may be formed of a conductive material having a hightransmittance. The p-type electrode is electrically connected to thefirst p-type semiconductor layer through the second p-type semiconductorlayer and the bonding layer.

The bonding layer may be formed of a non-conductive material having ahigh transmittance. A partial portion of the p-type electrode maypenetrate through the second p-type semiconductor layer and the bondinglayer to contact the first p-type semiconductor layer.

The first light emitting layer may be a green light emitting layer or ablue light emitting layer. The second light emitting layer may be a redlight emitting layer.

According to another aspect of the present disclosure, there is provideda wafer. The wafer includes a substrate. The wafer further includes aplurality of light emitting devices disposed on the substrate. Each ofthe plurality of light emitting devices includes a first n-typesemiconductor layer disposed on the substrate. Each of the plurality oflight emitting devices further includes a first light emitting layerdisposed on the first n-type semiconductor layer. Each of the pluralityof light emitting devices further includes a p-type semiconductor layerdisposed on the first light emitting layer. Each of the plurality oflight emitting devices further includes a second light emitting layerdisposed on the p-type semiconductor layer. Each of the plurality oflight emitting devices further includes a second n-type semiconductorlayer disposed on the second light emitting layer. Each of the pluralityof light emitting devices further includes a p-type electrode disposedon the p-type semiconductor layer. Each of the plurality of lightemitting devices further includes a first n-type electrode disposed onthe first n-type semiconductor layer. Each of the plurality of lightemitting devices further includes a second n-type electrode disposed onthe second n-type semiconductor layer.

the p-type semiconductor layer may include a first p-type semiconductorlayer disposed on the first light emitting layer. the p-typesemiconductor layer may further include a second p-type semiconductorlayer disposed on the first p-type semiconductor layer. Each of theplurality of light emitting devices may further includes a bonding layerdisposed between the first p-type semiconductor layer and the secondp-type semiconductor layer.

An entire portion of the second p-type semiconductor layer, an entireportion of the first p-type semiconductor layer, and an entire portionof the first light emitting layer may overlap the first n-typesemiconductor layer. An entire portion of the second n-typesemiconductor layer and an entire portion of the second light emittinglayer may overlap the second p-type semiconductor layer.

The first n-type electrode may be disposed on a partial portion of thefirst n-type semiconductor layer that does not overlap the first lightemitting layer. The p-type electrode may be disposed on a partialportion of the second p-type semiconductor layer that does not overlapthe second light emitting layer. The second n-type electrode may bedisposed between the first n-type electrode and the p-type electrode ona plane.

The first n-type electrode may have a larger thickness than the secondn-type electrode and the p-type electrode.

When a voltage is applied to the first n-type electrode and the p-typeelectrode, the first light emitting layer may emit light. when a voltageis applied to the second n-type electrode and the p-type electrode, thesecond light emitting layer may emit light. When a voltage is applied tothe first n-type electrode, the second n-type electrode, and the p-typeelectrode, the first light emitting layer and the second light emittinglayer may emit light.

The plurality of light emitting devices may include a first lightemitting device including a first green light emitting layer emittinggreen light as the first light emitting layer. The plurality of lightemitting devices may further include a second light emitting deviceincluding a first blue light emitting layer emitting blue light as thefirst light emitting layer. The first light emitting device may emit thegreen light from the first green light emitting layer and red light fromthe second light emitting layer. The second light emitting device mayemit the blue light from the first blue light emitting layer and the redlight from the second light emitting layer.

The first light emitting device and the second light emitting device maybe alternately disposed in the same row or in the same column.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the light emitting deviceand the wafer of the present disclosure without departing from thetechnical idea or scope of the disclosure. Thus, it is intended that thepresent disclosure cover the modifications and variations of thisdisclosure provided they come within the scope of the appended claimsand their equivalents.

What is claimed is:
 1. A light emitting device, comprising: a firstn-type semiconductor layer; a first light emitting layer disposed on thefirst n-type semiconductor layer; a first p-type semiconductor layerdisposed on the first light emitting layer; a second p-typesemiconductor layer disposed on the first p-type semiconductor layer; abonding layer disposed between the first p-type semiconductor layer andthe second p-type semiconductor layer; a second light emitting layerdisposed on the second p-type semiconductor layer; a second n-typesemiconductor layer disposed on the second light emitting layer; ap-type electrode disposed on the second p-type semiconductor layer; afirst n-type electrode disposed on the first n-type semiconductor layer;and a second n-type electrode disposed on the second n-typesemiconductor layer.
 2. The light emitting device according to claim 1,wherein a partial portion of the first n-type semiconductor layerprotrudes outward beyond the first light emitting layer, the firstp-type semiconductor layer, the second p-type semiconductor layer, thesecond light emitting layer, and the second n-type semiconductor layer,and the first n-type electrode is disposed on the partial portion of thefirst n-type semiconductor layer protruding outward beyond the firstlight emitting layer and the second light emitting layer.
 3. The lightemitting device according to claim 2, wherein an entire portion of thesecond p-type semiconductor layer overlaps the first light emittinglayer, a partial portion of the second p-type semiconductor layerprotrudes outward beyond the second light emitting layer and the secondn-type semiconductor layer, and the p-type electrode is disposed on thepartial portion of the second p-type semiconductor layer protrudingoutward beyond the second light emitting layer.
 4. The light emittingdevice according to claim 1, wherein the first n-type electrode has alarger thickness than the second n-type electrode.
 5. The light emittingdevice according to claim 4, wherein the first n-type electrode isformed of an opaque conductive material, and the second n-type electrodeis formed of a transparent conductive material.
 6. The light emittingdevice according to claim 1, wherein the bonding layer is formed of aconductive material having a high transmittance, and the p-typeelectrode is electrically connected to the first p-type semiconductorlayer through the second p-type semiconductor layer and the bondinglayer.
 7. The light emitting device according to claim 1, wherein thebonding layer is formed of a non-conductive material having a hightransmittance, and a partial portion of the p-type electrode penetratesthrough the second p-type semiconductor layer and the bonding layer tocontact the first p-type semiconductor layer.
 8. The light emittingdevice according to claim 1, wherein the first light emitting layer is agreen light emitting layer or a blue light emitting layer, and thesecond light emitting layer is a red light emitting layer.
 9. A wafer,comprising: a substrate; and a plurality of light emitting devicesdisposed on the substrate, wherein each of the plurality of lightemitting devices includes: a first n-type semiconductor layer disposedon the substrate; a first light emitting layer disposed on the firstn-type semiconductor layer; a p-type semiconductor layer disposed on thefirst light emitting layer; a second light emitting layer disposed onthe p-type semiconductor layer; a second n-type semiconductor layerdisposed on the second light emitting layer; a p-type electrode disposedon the p-type semiconductor layer; a first n-type electrode disposed onthe first n-type semiconductor layer; and a second n-type electrodedisposed on the second n-type semiconductor layer.
 10. The waferaccording to claim 9, wherein the p-type semiconductor layer includes: afirst p-type semiconductor layer disposed on the first light emittinglayer; and a second p-type semiconductor layer disposed on the firstp-type semiconductor layer, and each of the plurality of light emittingdevices further includes a bonding layer disposed between the firstp-type semiconductor layer and the second p-type semiconductor layer.11. The wafer according to claim 10, wherein an entire portion of thesecond p-type semiconductor layer, an entire portion of the first p-typesemiconductor layer, and an entire portion of the first light emittinglayer overlap the first n-type semiconductor layer, and an entireportion of the second n-type semiconductor layer and an entire portionof the second light emitting layer overlap the second p-typesemiconductor layer.
 12. The wafer according to claim 11, wherein thefirst n-type electrode is disposed on a partial portion of the firstn-type semiconductor layer that does not overlap the first lightemitting layer, the p-type electrode is disposed on a partial portion ofthe second p-type semiconductor layer that does not overlap the secondlight emitting layer, and the second n-type electrode is disposedbetween the first n-type electrode and the p-type electrode on a plane.13. The wafer according to claim 12, wherein the first n-type electrodehas a larger thickness than the second n-type electrode and the p-typeelectrode.
 14. The wafer according to claim 9, wherein when a voltage isapplied to the first n-type electrode and the p-type electrode, thefirst light emitting layer emits light, when a voltage is applied to thesecond n-type electrode and the p-type electrode, the second lightemitting layer emits light, and when a voltage is applied to the firstn-type electrode, the second n-type electrode, and the p-type electrode,the first light emitting layer and the second light emitting layer emitlight.
 15. The wafer according to claim 9, wherein the plurality oflight emitting devices includes: a first light emitting device includinga first green light emitting layer emitting green light as the firstlight emitting layer; and a second light emitting device including afirst blue light emitting layer emitting blue light as the first lightemitting layer, the first light emitting device emits the green lightfrom the first green light emitting layer and red light from the secondlight emitting layer, and the second light emitting device emits theblue light from the first blue light emitting layer and the red lightfrom the second light emitting layer.
 16. The wafer according to claim15, wherein the first light emitting device and the second lightemitting device are alternately disposed in the same row or in the samecolumn.